{ config, lib, pkgs, modulesPath, ... }:

{
  imports = [
    "${modulesPath}/installer/sd-card/sd-image.nix"
  ];

  #boot.kernelPackages = pkgs.linuxPackages_latest;
  boot = {
    kernelPatches = [
      {
        name = assert false; "sbi-early-console";
        patch = null;
        extraConfig =
        # Early console via SBI
        ''
          RISCV_SBI y
          RISCV_SBI_V01 y
          SERIAL_EARLYCON y
          SERIAL_EARLYCON_RISCV_SBI y
          HVC_DRIVER y
          HVC_RISCV_SBI y
        ''
        # Allows regions of persistent memory to be described in the device-tree.
        + ''
          OF_PMEM y
        ''
        # Allow you to use a contiguous range of reserved memory as one or more
        # persistent block devices (/dev/pmem0)
        + ''
          LIBNVDIMM y
          BLK_DEV_PMEM y
        ''
        ;
      }
    ];

    initrd = {
      # Avoid zstd as we don't have the tools in "cucu" machine
      compressor = "gzip";
      kernelModules = [ ];
    };

    loader = {
      grub.enable = false;
      generic-extlinux-compatible.enable = true;
    };
  };

  # No network
  services.openssh.enable = false;

  # Run getty on /dev/console and restartt until it works
  systemd.services."serial-getty@console" = {
    enable = true;
    wantedBy = [ "getty.target" ]; # to start at boot
    serviceConfig.Restart = "always";
  };

  sdImage = {
    # The image will be loaded as-is in memory, so no compression
    compressImage = false;
    imageName = "rootfs.img";
    # Not needed for now
    expandOnBoot = false;
    populateFirmwareCommands = "";
    populateRootCommands = ''
      mkdir -p ./files/boot
      ${config.boot.loader.generic-extlinux-compatible.populateCmd} \
        -c ${config.system.build.toplevel} \
        -d ./files/boot
    '';
  };

  nixpkgs.overlays = [ (final: prev: {
    uboot = prev.ubootQemuRiscv64Smode.override {
      filesToInstall = [ "u-boot.bin" "u-boot-nodtb.bin" ];
      extraConfig = ''
        CONFIG_RISCV_ISA_C=n
        CONFIG_REQUIRE_SERIAL_CONSOLE=n
        CONFIG_SERIAL_SEARCH_ALL=y
        CONFIG_OF_CONTROL=y
        CONFIG_OF_BOARD=y
        CONFIG_OF_HAS_PRIOR_STAGE=y
        CONFIG_BLKMAP=y
        CONFIG_CMD_BLKMAP=y
        CONFIG_SBI_V01=y
        CONFIG_DEBUG_UART=y
        CONFIG_DEBUG_UART_ANNOUNCE=y
        CONFIG_DEBUG_SBI_CONSOLE=y
      '';
    };

    uboot-env = let
      init = "${config.system.build.toplevel}/init";
      initrd = "${config.system.build.initialRamdisk}/initrd";
    in prev.runCommand "uboot.txt" {} ''
      cat > $out <<EOF
      # Create pmem
      fdt mknode / pmem@0x180000000
      fdt set /pmem@0x180000000 compatible "pmem-region"
      fdt set /pmem@0x180000000 reg <0x1 0x80000000 0x0 0x80000000>

      # Reduce memory
      fdt set /memory@80000000 reg <0x00000000 0x80000000 0x00000001 0x00000000>

      # Set kernel options
      setenv bootargs "root=/dev/ram0 loglevel=7 debug rw earlycon=sbi boot.trace console=hvc0 init=${init}"

      EOF

      # Populate the bood commands from the initrd size
      echo "# Boot system" >> $out
      echo "setenv ramdisk_size $(stat --format %s $(readlink -f ${initrd}))" >> $out
      echo 'booti ''${kernel_addr_r} ''${ramdisk_addr_r}:''${ramdisk_size} ''${fdtcontroladdr}' >> $out
    '';

    opensbi = prev.opensbi.overrideAttrs (old: {
      makeFlags = old.makeFlags ++ [
        "PLATFORM=fpga/openpiton"
        "FW_PAYLOAD_PATH=${final.uboot}/u-boot-nodtb.bin"
      ];
    });
  }) ];
}